How to fix macOS Big Sur Boot Loop (Keep Restarting)?

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What comes along with the new macOS Big Sur not only includes the new attractive features and look, but also a series of boot issues. One of the most discussed problems is that a MacBook Pro bricked and stuck in a boot loop.

This is an awful situation after mac OS 11 updates as every time the Mac starts up, and I log in, then it just completely turns off and reboots over again and again.

But I have to say, this is normal during the big sur update (at least in my case). It keeps restarting for four or five times, then black screen. But it finally goes through this loading process with my patience.

If your Mac didn’t servive from the boot loop like me and normal fixes like Safe mode and resetting SMC can’t help, here are some clues to save Mac from the boot loop.

1. Choose the right startup disk

One possible cause for macOS Big Sur stuck in a boot loop is that the machine doesn’t find a startup disk to boot this Mac.

For example, when prompted, choosing the Macintosh-Data volume from the list of volumes won’t boot the Mac up. This happens frequently as most users don’t know that Apple split the operating system and user’s data into two volumes.

To save the Mac from a boot loop, restart the Mac and press the Option key at the same time, choose the right startup disk (often named Macintosh HD or macOS).

2. Unlock the startup disk from macOS Recovery mode

Sometimes macOS Big Sur won’t boot past the apple logo just because the startup disk is encrypted. Then, all you need to do is to unlock it and make it bootable in recovery mode with these steps:

• Boot Mac into recovery mode by pressing Command + R at startup
• Choose the Apple logo to select a startup disk
• Unlock it with the password and restart. If this won’t work, try to unlock the disk in Disk Utility instead.
• Choose Disk Utility from the macOS Utilities
• Select the startup disk that is encrypted by FileVault and choose Mount
• When it’s prompted, fill in the correct password to a FileVault-enabled account on the drive
• If the authentication is accepted, the drive should unlock and mount.
• Restart the Mac

Here is how to boot into macos recovery mode on Apple Silicon Macs with macOS Big Sur.

3. Reinstall macOS

Also, the Mac might get stuck on finding the right startup disk, or it fails at the Apple logo. Also, the prohibitory symbol at startup is another case, which occurs if the macOS on the startup disk is too old, too new, too corrupted.

If your Mac is stuck in a boot loop after the macOS Big Sur update, what I advise is to, check if your machine is compatible with this new system first.

Assuming your machine works with macOS Big Sur, the solution to this problem ends up with disk repair and system reinstallation from macOS recovery mode.

Here is how to downgrade macOS Big Sur to Catalina or other compatible systems.

• Force the Mac to shut down and then hold Command + R at the restart
• Open Disk Utility from macOS Utilities and select the startup disk
• Click on First Aid to check and repair if any corruption inside the disk
• Restart your Mac to see If it goes past the boot loop this time. If not, you end up with disk erasure and macOS reinstallation, which will clean the data on the computer. (Do not erase disk in Disk Utility if it’s an M1 Mac)
• Boot into macOS Recovery mode again > Disk Utility > Erase.
• Then from the macOS Utilities, choose Reinstall macOS.

Note: After downgrading your macOS, you could use CleanMyMac X to remove gigabytes of junk, hidden files, old archives left by the old Big Sur operating system, which will prevent problems caused by residual data.

When Mac keeps restarting after a recent macOS Big Sur update (especially for the Beta version) and won’t get out of a boot loop, unlocking the startup disk is proven the most effective solution.

Please let me know if any solution works for you.